Epothilone derivatives of the following formula are useful as an anti-cancer agent.

In synthesis of Epothilone derivatives, optically active (S)-7-hydroxy-6-methylheptan-2-one is useful as a C7 to C12 building block, and this compound can be derived from optically active (S)-2-methyl-6-oxoheptanoic acid via its ester (see, patent documents 1 and 2, non-patent documents 1 and 2). For 2-methyl-6-oxoheptanoic acid, various production methods are suggested (see, non-patent documents 3 to 8). In the production methods described in non-patent documents 3 to 6, however, raw material availability is problematic since corresponding natural materials are extracted and isolated, and oxidized in these methods. The production method described in non-patent document 6 is a method of producing a (R) body. The production methods described in non-patent documents 7 and 8 are methods for oxidizing 2,6-dimethylcyclohexanone using potassium permanganate, however, the resultant product is a racemate of 2-methyl-6-oxoheptanoic acid, and is optically inactive.
[patent document 1] DE 19751200
[patent document 2] WO 2005/003071
[non-patent document 1] J.A.C.S., 119, 7974 (1997)
[non-patent document 2] Chem. Eur. J., 2, 1477 (1996)
[non-patent document 3] Natural Product Letters, 3, 189 (1993)
[non-patent document 4] J. Nat. Prod., 66, 251 (2003)
[non-patent document 5] Natural Product Letters, 4, 51 (1994)
[non-patent document 6] Helv. Chim. Acta, 73, 733 (1990)
[non-patent document 7] J. Med. Chem., 26, 426 (1983)
[non-patent document 8] Collect. Czech. Chem. Commun., 30, 1214 (1965)